Effect of surfactant type and droplet size on lipid oxidation in oil-in-water nano-emulsions

Abstract

The effect of surfactant type and droplet size on the oxidative stability of extra virgin olive oil (EVOO) in bitter orange juice nano-emulsions [10% (w/w) oil phase] (O/W) was investigated. Nano-emulsions stabilised with binary combinations of Tween80, Span20, sucrose monopalmitate (SMP) and sunflower lecithin (SL) were prepared by using phase inversion composition. Thermal oxidation profile of unprocessed EVOO was determined by using the non-isothermal differential scanning calorimetry (DSC) method at five different heating rates over a temperature range of 40-400 °C. Oxidative stability was determined by using the isothermal DSC method at 110, 120, 130 and 140 °C. Temperature dependency of lipid oxidation was shown by using the Arrhenius equation. Droplet size and surfactant type significantly influenced the lipid oxidation. The best oxidative stability was observed in unprocessed EVOO, followed by Tween80/SL nano-emulsion, Tween80/SMP nano-emulsion and Tween80/Span20 nano-emulsion, respectively.